Kwapniowski fraudulently invoiced the hospital more than 220 times between 2012 and 2018, prosecutors said.

Sometime before 2010, Kwapniowski submitted to the hospital fraudulent invoices from legitimate pharmaceutical suppliers, according to court records. She later submitted reimbursement requests utilizing fraudulent invoices from a company she fraudulently created. Some of the invoices were for a fake drug.

Prosecutors said she also submitted fraudulent invoices that appeared to come from a legitimate drug vendor and used fraudulent means to obtain payments.

Kwapniowski is scheduled to be sentenced April 29. She faces up to 20 years in prison and a fine of up to $250,000. She'll be ordered to pay restitution as part of her sentence, prosecutors said.

Children's Hospital and Medical Center released a statement saying officials were happy with the outcome.

"We appreciate the work of law enforcement and the United States Attorney's Office on this matter and we are confident that Ms. Kwapniowski will be held accountable for her actions," the hospital said. "This was the first time an event of this nature has occurred in our 70-year history, and we remain staunchly committed to proper fiduciary management and stewardship."

Kwapniowski was fired in June after accusations arose. The state has also revoked her license to practice pharmacy for at least two years. Her reinstatement would have to be approved by the Nebraska Board of Pharmacy.